My article Top 10 FAQs for Admins about BCS just got published at SharePointProConnections:
Thanks to Business Connectivity Services (BCS), it’s now easy to integrate external data into SharePoint 2010. If you’re a SharePoint administrator keen to know what BCS is, what it offers, and how to manage it in your SharePoint environment, this top 10 list is for you.
Can a BCS handles more than 1 web applications?
for example I have 8 web applications and all of them have a similar database structure. Can I use the same BCS service for all of them even if each of them have their on different connection strings?
@William – You need to add the BCS Service Application to the web application proxy group (Service Application Associations). You can find more info here – http://technet.microsoft.com/en-us/library/ee704550.aspx